The present invention relates to a device for transferring current between two end points between which a ribbon cable extends, wherein the ribbon cable serves for an electrical connection and is contained in a cassette in coiled form. The cable has at least two electric wires the length of which is substantially greater than the distance between the two end points. At least one of the two end points is movable relative to the other. Plugs are connected in electrically conductive manner to the bared wires of the ribbon cable at at least one end, the plugs being arranged in a prefabricated housing of insulating material which is provided on one end with an opening to receive mating contacts such a device being disclosed in German Utility Model 89 14 423.
Apparatus having such devices comprise, for instance, winders in which an electric cable is wound on a reel. The cable can be pulled out of the housing of the apparatus and automatically rolled up again under the action of a spring after the cessation of a pulling force. This apparatus can also be employed for the feeding of current for crash protection in motor vehicles in which an electric cable is arranged in the steering wheel of a vehicle. One essential problem with these apparatus is the transfer of current between stationary and movable parts. This problem is present in all apparatus in which there are two end points which are movable relative to each other, one of them in most cases being developed as a fixed point. The wiper contacts or wiper rings, known for a long time for use in such cases, are subject to wear and are disadvantageous particularly in the case of low current intensities due to varying contact resistances.
In the known device in accordance with the aforementioned German Utility Model 89 14 423, the transfer of current takes place by the ribbon cable which is wound, for instance, in the manner of a spring barrel. Upon a turning relative to each other of the two end points which are connected by the ribbon cable, the wound ribbon cable "breathes" like the spring of a watch. The turns are contracted to a small diameter in one direction of rotation. In the other direction of rotation they return to a larger diameter. By the application of the plugs to at least one end of the ribbon cable, extension cables equipped with corresponding mating contacts can easily be attached. Upon a placing of mating contacts on the connecting plugs and their removal from them, forces which act particularly in axial direction are exerted on the plugs. As a result, the connecting places between the wires of the ribbon cable and the plug pins can be subjected to load and possibly damaged. No measures by which this can be avoided are indicated in the aforementioned German Utility Model 89 14 423.